131665878 has 32 divisors (see below), whose sum is σ = 293149920. Its totient is φ = 43804800.

The previous prime is 131665841. The next prime is 131665889. The reversal of 131665878 is 878566131.

131665878 is a `hidden beast` number, since 1 + 3 + 1 + 66 + 587 + 8 = 666.

131665878 is a nontrivial binomial coefficient, being equal to C(16228, 2).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30426 + ... + 34482.

It is an arithmetic number, because the mean of its divisors is an integer number (9160935).

Almost surely, 2^131665878 is an apocalyptic number.

131665878 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

131665878 is the 16227-th triangular number and also the 8114-th hexagonal number.

131665878 is an abundant number, since it is smaller than the sum of its proper divisors (161484042).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

131665878 is a wasteful number, since it uses less digits than its factorization.

131665878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4669 (or 4663 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The square root of 131665878 is about 11474.5752862579. The cubic root of 131665878 is about 508.7343704286.

It can be divided in two parts, 13166 and 5878, that added together give a square (19044 = 138²).

The spelling of 131665878 in words is "one hundred thirty-one million, six hundred sixty-five thousand, eight hundred seventy-eight".